A mobile communication system such as a portable telephone system or a wireless local area network (WLAN) is utilized widely at present. Further, in the field of mobile communication, ongoing discussions have been and are being conducted on the next generation communication technology in order to further improve the communication speed, communication capacity and communication quality. For example, by the 3rd generation partnership project (3GPP) that is a standardization organization, standardization of communication standards called long term evolution (LTE) or communication standards called LTE-advanced (LTE-A) based on LTE is completed or being investigated.
In a mobile communication system, maintenance or assurance of stabilized communication quality sometimes depends upon the situation of a user who utilizes the mobile communication system or the communication environment of a cell visited by a terminal apparatus.
For example, advanced medical equipment such as a computed tomography (CT) scanner is being incorporated into an ambulance or the like, and when a patient is transported to a hospital by such an ambulance, a large amount of information is sometimes transmitted to the hospital. However, in a transport process from the accident site to the hospital, the accident site may be crowded with onlookers, and therefore, when the ambulance moves, congestion of communication may occur.
Not only in the example of transportation by an ambulance, but also in various situations in viewing services of moving pictures or handling of big data, congestion of communication has come to occur together with explosive growth of smartphones and so forth. Congestion of communication sometimes causes, for example, packet loss, and increased time may be required until a normal packet reaches the reception side. Accordingly, congestion of communication makes maintenance and assurance of stabilized communication quality difficult.
Further, reservation and guarantee of a bandwidth by mass transmission of mass information, reservation and guarantee of a bandwidth by mass transmission upon handover, a mechanism for billing commensurate with the used bandwidth and so forth are demanded.
On the other hand, in the field of mobile communication, self-similarity of the traffic sometimes appears. For example, if a packet error or the like occurs, then a base station apparatus sometimes performs retransmission control such as, for example, automatic repeat request (ARQ) or hybrid ARQ (HARQ) to transmit a packet with which an error has occurred to a terminal apparatus again. In this case, even if the base station apparatus performs retransmission control, a packet error sometimes occurs again. The self-similarity signifies a situation in which, for example, when an error occurs in this manner, even if it is tried to recover the error, a same error occurs again and this is repeated.
In the field of mobile communication described above, for example, such technologies as described below are available.
In particular, a packet loss prediction apparatus is available wherein a delay fluctuation is calculated from a transmission interval and a reception interval of packets and, when the value of the delay fluctuation continues for a period longer than a first given length within a range of abnormal values, it is predicted that there is the possibility that packet loss may have occurred.
With this technology, it is considered that occurrence of packet loss can be predicted in real time communication.
Further, a communication system is available wherein light congestion or heavy congestion is detected at the communication terminal side, and even when light congestion is detected, a window for determining a packet transmission amount is increased and a lost packet is sent again.
With the technology just described, it is considered that the throughput can be increased even in a high loss rate state without a notification of special congestion information from a network. As related art documents, Japanese Laid-open Patent Publication No. 2012-186772 and Japanese Laid-open Patent Publication No. 2007-208571 are available.